Bletchley Park is now a museum, the original buildings originally a secret government site built on the grounds of a stately home near the town of Milton Keynes in Buckinghamshire, England, about 50 miles north of London. It is situated in the town of Bletchley.

During World War II, Bletchley Park was the site of the United Kingdom's efforts to break Axis ciphers, particularly the Enigma and Lorenz ciphers used by Nazi Germany. The estate was conveniently located midway between the universities of Oxford and Cambridge, which supplied many of the codebreakers.

Bletchley Park has been attributed with reducing the war by 2 years, ending the bombing of Pearl Harbour by sending information of the location of Yamamoto the head of the Japanese North Atlantic Fleet. Montgomery would often talk of how the code breaking efforts of Bletchley Park enabled him to 'know what the Jerry's are having for breakfast'.

The Government Code and Cypher School (GC & CS), the intelligence bureau responsible for interception and decryption of foreign transmissions, moved into the Park in 1938. The radio station constructed in the park for its use was given the codename "Station X" — this term is often erroneously applied to the code-breaking efforts at Bletchley as a whole. Station X was soon moved south to Whaddon Hall, to prevent any attention being drawn to the Bletchley site. To further the disguise of bletchley park it was built to appear as a Hospital from above so to deter bombing by German planes, however there was a bomb dropped next to the despatch riders entrance shifting the whole of Hut 4 (the Naval Intelligence hut) 2 meters on its base. The bomb was thought to have been dropped to hit the Bletchley Train station.

The first Government visitors to Bletchley Park somewhat clumsily (and suspiciously) described themselves as members of Captain Ridley's shooting party. The code-name for the intelligence produced via decrypts at Bletchley was "ULTRA".

Among the famous mathematicians and cryptanalysts working there, perhaps the most influential and best-known was Alan Turing. In 1943, the computer Colossus computer was designed at Bletchley Park by Max Newman and his team; it was the world's first programmable digital electronic computer. The computer was designed and built to help break the Lorenz cipher. Tommy Flowers is said to be the biggest influence on the building of an electronic computer as he introduced the electronic valve - a device, until use in the colossus, considered as being unreliable.

It is thought that at the height of the codebreaking efforts during the war, more than 10,000 people worked at Bletchley Park. Those who worked in Bletchley park were selected for various intellectual acheievements whether they were chess champions, crossword experts, multilinguists or great mathematicians. The workers were known to complete a 5 year course of Japanese in just 6 months.

The codebreakers would enter the park by coaches or train, it is rumoured that there were a series of inter-connecting tunnels and chambers below Bletchley park which allowed workers to get in secretly. It is rumoured one tunnel was for the use of Winston Churchill, which started in the Park grounds and emerged in the local pub. It is also said Eisenhower and Churchill had a meeting in one of the rumoured chambers.

The Bletchley Park effort was comparable in influence to other WW II-era technological efforts, such as the crytographic work at Arlington Hall/Naval Communications Annex, the development of microwave radar at MIT's Radiation Lab, and the Manhattan Project's development of nuclear weapons.

At the end of the war, much of the equipment used and its blueprints were destroyed by order of Churchill. Though thousands of people were involved in the decoding efforts, the participants remained silent for decades about what they had done during the war, and it was only in the 1970s that the work at Bletchley Park was revealed to the general public. After the war, the site belonged to several owners, including British Telecom and the Civil Aviation Authority 1.

The Bletchley Park Trust has been founded to further the maintenance of the site as a museum devoted to the codebreakers. The Trust is volunteer based and relies on public support to continue its efforts.

Before Station X
The Bletchley Park estate had been a manor since the Norman invasion. The earliest known reference is in 1308 2, when it was owned by the de Grey family. It is also known that Browne Willis was lord of the manor in the early 18th century, some of his buildings (now lost) dating from 1711. The manor was at some time appropriated by the Crown. The present mansion was built between 1883 and 1926 by Herbert Samuel Leon (1850-1926), a financier and Liberal MP, who extended the red brick farmhouse of 1860 3. Its style is a mixture of Victorian Gothic, Tudor and Dutch Baroque and was the subject of much bemused comment from those who worked there, or visited, during WWII. Leon's estate covered 581 acres (235 hectares), of which Bletchley Park occupied about 55 acres (22 hectares). Leon's wife died in 1937 4, and in 1938 the site was sold to a builder, who was about to demolish the mansion and build a housing estate when the War began, and the Government Property Agency 5 requisitioned the site.
Hugh Sebag-Montifiore, author of the recent book "Enigma", is Leon's grandson. His book contains several photographs of the manor, before, during, and after WWII.